1. Field
The present disclosure relates to an insulator that electrically insulates a stator core, including a plurality of electrical steel plates that are stacked, from a coil wire.
2. Description of the Related Art
In a stator of existing rotating electric machines, a resin insulator is disposed between a tooth of a stator core, including a plurality of electrical steel plates that are stacked in the axial direction, and a coil wire, which is wound around the tooth, to electrically insulate the stator core from the coil wire.
For the stator, the space factor of the coil wire is important in increasing the magnetomotive force of a rotating electric machine. Reducing the thickness of the insulator is effective in increasing the space factor. However, reduction in the thickness of the entirety of an insulator is limited, because the insulator is usually made by molding a resin. For this reason, some insulators disclosed to date include a portion that is made from an insulating sheet, such as an insulating film or an insulating paper (see, for example, International Publication No. 2013/133337 and Japanese Unexamined Patent Application Publication No. 2011-234537).
The insulators described in International Publication No. 2013/133337 and Japanese Unexamined Patent Application Publication No. 2011-234537 include a tubular body, which is made from an insulating film, and resin flanges, which are integrally molded with the body by insert molding. In these insulators, by making the body from a thin insulating film so as to surround a tooth, the space factor of a coil wire wound around the tooth is increased.
A stator core that is made by stacking a plurality of electrical steels or the like in the axial direction inevitably has a variation in the dimension in the stacking direction. The insulator described in International Publication No. 2013/133337, which includes a pair of segments that are substantially U-shaped and assembled in the circumferential direction, is not capable of accommodating the variation in the thickness of the stator core in the stacking direction. Therefore, considering the variation in the thickness of an iron core portion in the stacking direction, it is necessary to form the insulator so as to have an allowance of the length in the stacking direction so that the insulator can be attached to the core portion even if the stacking thickness becomes the maximum due to the variation. In this case, however, when winding a coil wire around the insulator, parts of the insulator between turns of the coil wire may become deformed do to the tension of the coil wire and the insulating film may be damaged. This damage might negatively affect the performance of the rotating electric machine.
Japanese Unexamined Patent Application Publication No. 2011-234537 describes an insulator according to an embodiment in which a body, which is made of an insulating film, and a resin flange are integrated with each other by performing insert molding by disposing the insulating film in an insert molding die. Also in this case, as with International Publication No. 2013/133337, it is not possible to accommodate the variation in the dimension in the stacking direction.
Japanese Unexamined Patent Application Publication No. 2011-234537 also describes an insulator according to another embodiment including a pair of segments that are substantially U-shaped and assembled in the stacking direction. Although this insulator is capable of accommodating the variation in the dimension in the stacking direction, fitting portions of the segments are located above and below a coil-wire-disposing region formed between circumferential-direction end surfaces, which are adjacent to each other. Moreover, because the segments need to overlap each other in the fitting portions, thickness is increased at the overlapping portion, and the space factor of a coil wire might decrease.